package com.mrzhou.study;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.regex.Pattern;

public class TempMain {

    public static void main(String[] args) {
        Integer[] root = {3, 9, 20, null, null, 15, 7};


        List<List<String>> obj = new ArrayList<>();


    }

}


